Write-once optical storage disks, such as optical disks, are distinguished from magnetic disks, magneto-optical disks and other erasable storage media in that the data, once written, cannot be erased or moved. At the same time, optical recording systems are subject to errors from the many varying conditions that can affect the read/write head and the reflected laser beam as the data is written to or read from the disk.
For this reason, elaborate error correction codes have been devised to correct for such errors and to assure that the bit stream which is output by the disk drive is an exact replica of the bit stream that was previously received by the drive and written to the disk. One such coding scheme is described in the Standard ECMA-279 (December 1998), which describes the error correction code (ECC) used in recordable DVD technology.
While these error correction codes work well with errors of relatively short duration, they do not deal effectively with longer lasting errors, such as errors that occur when the drive is subjected to a physical shock or the flow of incoming data is interrupted during a write operation.
Accordingly, there is a need for an error management system that is able to correct relatively long lasting errors that occur while writing on a write-once data storage disk.